First off, all i have to say about that finale is WOW. Maybe with a WTF thrown in for flavour. Secondly, i've been thinking on how Season 4 will start...
Two options. It can pick up where it left off; after a respectable amount of time... or it can go Full Whedon and basically do Dollhouse, Epitaph 2.
Yeah, I doubt that'll happen either. PoI straddles an exquisite line between its relevancy with today's technology and fears and its balls-to-the-wall sci-fi.
I am confident there will be one of say 6-12 months though.
But just think what a vaguely post-Samaritan future might look like after 10 years of its 'domination'... maybe shades of the Observer Future perhaps?
...or maybe, just to completely mess with our heads, it turns out it actually a pretty nice place to live (if you've got nothing to hide!). :p
Is it possible to find a halfway point between these two? I think showing an obvious form of totalitarian state would be a little too on the nose and might ruin what make PoI great.... but at the same times, they've really changed the game and simply showing a continual stream of police/alphabet raids on seemingly random people doesn't really stoke the fires, ya know?
However, it turns out though, the writers are making it harder and harder on themselves with every excellent episode they crank out!